Production process of optical disc and optical disc produced thereby

ABSTRACT

A production process of an optical disk, wherein when a layer of an ultra violet rays curing resin which constitutes a portion of the optical disk is formed, a semi-transparent film of a metal is formed on a molded substrate on which a pattern was transcribed and this molded substrate is used as a semi-transparent stamper, and the production of an optical disk with two layers at one side is made easy thereby.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2001-254667, filed Aug. 24, 2001, the entire contents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates to a production process of an optical disk with two layers at one side using an ultra violet rays curing resin (2P resin: Photo-Polymer) and an optical disk which was produced thereby.

[0004] 2. Description of the Related Art

[0005] Various modes have been recently designed in accordance with a request for making a high capacity optical disk, but there is an optical disk, of which one side was doubly layered, is shown in Japanese Patent Application Laid-Open No. 10-283682, as one of the methods. A process for producing the optical disk using an ultra violet rays curing resin (hereinafter, described as 2P resin) which is cured by the irradiation of ultra violet rays is adopted as the present production process of an optical disk with two layer at one side.

[0006] The production process is illustrated below. Firstly, a semi-transparent film is formed on a molded substrate on which a pattern for the first layer was transcribed. A 2P resin is coated on the layer, a nickel stamper is pushed on the 2P resin, ultra violet rays are irradiated to cure it, and then the second layer is transcribed.

[0007] The prior art is characterized in that in order not to peal the 2P resin from the first layer at pealing the stamper from the 2P resin, an adhesive layer is provided between them.

[0008] Since the present DVD (Digital Versatile Disk) which is subject to the incidence of laser light from a molded substrate side is assumed in the prior art, is adopted a process in which the first layer on the molded substrate becomes semi-transparent, then the 2P resin is sandwiched by a nickel stamper and ultra violet rays are irradiated to cure it.

[0009] However, a side which receives the incidence of laser light is the reverse side of the molded substrate in the next generation DVD, therefore it is the reverse side of the current method. Accordingly, the total reflection film of the second layer is formed on the molded substrate, and if the 2P resin is sandwiched by the nickel stamper, the 2P resin cannot be cured because ultra violet rays are not transmitted through the total reflection film.

[0010] As a counter measure for this, the use of a transparent stamper by a quartz is shown in Japanese Patent Application Laid-Open No. 4-372741, but the quartz must be etching process in order to prepare the stamper, it cannot be prepared in the usual production process of an optical disk, therefore a special facility is required.

[0011] Namely, according to the conventional production process of an optical disk, in case of producing a two layered disk using the 2P resin, when the total reflection film is provided as the film of the molded substrate side, the 2P resin comes to be sandwiched by the opaque total reflection film and the nickel stamper, therefore even if ultra violet rays are irradiated, they cannot be transmitted and reach the 2P resin. Accordingly the conventional production process of an optical disk has a problem that the 2P resin of the next generation optical disk with two layers at one side cannot be cured by ultra violet rays.

[0012] Further, since a step of etching a quartz and the like occurs in order to form a stamper in the conventional production process of the latter, it is not prepared in the usual production process of an optical disk, a special facility is required, and it costs high, therefore there is a problem that the stamper cannot be easily produced and prepared in large quantities.

BRIEF SUMMARY OF THE INVENTION

[0013] The object of the present invention is to easily produce the next generation optical disk with two layers at one side by forming a transparent stamper by injection molding which is the production process of an optical disk, preparing a semi-transparent stamper which was obtained by depositing a semi-transparent metal thin film on it, and using the semi-transparent stamper at curing by ultra violet rays of 2P resin.

[0014] The present invention is the production process of an optical disk, wherein when the layer of an ultra violet rays curing resin which constitutes the portion of the optical disk is formed, the semi-transparent film of a metal is formed on a molded substrate on which a pattern was transcribed and this molded substrate is used as a semi-transparent stamper.

[0015] According to the present invention, since the stamper is a semi-transparent stamper prepared by a resin, it transmits ultra violet rays which the nickel stamper of a conventional apparatus does not transmit, and even if the total reflection film of a metal is formed at a molded substrate as the next generation optical disk and ultra violet rays cannot be irradiated from this side, the ultra violet rays are irradiated through the semi-transparent stamper and the 2P resin can be cured. Further, since the semi-transparent stamper can be prepared in one process of the production of an optical disk by injection molding which is the production process of an optical disk, disposable semi-transparent stampers can be easily produced in large quantities. Accordingly, it is advantageous from the viewpoint of cost, a stamper in an optimum condition is always utilized and the sure production of an optical disk can be carried out.

[0016] Further, the present invention is an optical disk having an ultra violet rays curing resin layer, equipped with at least a first substrate; a first thin film layer which was formed on the first substrate; and the layer of the ultra violet rays curing resin which was cured by irradiation of ultra violet rays using a semi-transparent stamper in which a semi-transparent metal film is formed on a transparent molded substrate which was formed on the first metal thin film layer and on which a pattern was transcribed.

[0017] According to the present invention, it is a next generation optical disk with two layers at one side, but since the semi-transparent stamper which was obtained by forming a semi-transparent metal film on a transparent molded substrate on which a pattern was transcribed is used, the 2P resin which is an ultra violet rays curing resin which could not be used in a conventional nickel stamper can be used even if it has the structure of two layers at one side. Thus, an optical disk having high reliability and being capable of suppressing cost for a stamper can be provided.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

[0018]FIG. 1 is a view showing one mode of operation of the production process of an optical disk which is related to the present invention;

[0019]FIGS. 2A and 2B are views for illustrating the action and effect of the production process of an optical disk which is related to the present invention;

[0020]FIG. 3 is a view showing one mode of operation of the next generation optical disk according to the production process of an optical disk which is related to the present invention; and

[0021]FIG. 4 is a view showing an example of the next generation optical disk according to the production process of an optical disk which is related to the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0022] The production process of an optical disk which is the mode of operation of the present invention is illustrated in detail below referring to the drawings. FIG. 1 is a view showing one mode of operation of the production process of an optical disk which is related to the present invention; FIGS. 2A and 2B are views for illustrating the action and effect; and FIG. 3 and FIG. 4 are views showing an example of the next generation optical disk according to the production process of an optical disk which is related to the present invention.

[0023] The production process of a two-layered optical disk which is related to the present invention is illustrated according to FIG. 1. It is assumed in the mode of operation that it is the next generation optical disk with two layers at one side to which the incidence of laser light is carried out from a cover layer 18 side. As shown in FIG. 3 and FIG. 4, the next generation optical disk is a disk to which laser light is irradiated from a cover layer side, and a reflection film 31 is formed on a molded substrate 31 in the optical disk of FIG. 3, and a cover layer 33 is further provided. The total reflection film 42 of Layer 1 is formed on a molded substrate 41 in the optical disk or FIG. 4, a semi-transparent film 44 of Layer 0 is further formed on an intermediate layer 43, and a cover layer is further provided. The production process of an optical disk which is illustrated below makes an optical disk with two layers at one side which is shown in FIG. 4, an objective. In FIG. 1, the total reflection film 12 is formed on Layer 1, namely the first molded substrate 11, and a semi-transparent film 17 is formed on Layer 0, namely the 2P resin layer 16.

[0024] Firstly, the first molded substrate 11 which becomes Layer 1 is formed (S1). At this time, a polycarbonate, PMMA (poly methyl methacrylate)), an amorphous polyolefin and the like are usually used as a material. The information pattern of Layer 1 is transcribed on the surface of the molded substrate. The pattern is transcribed by mounting a nickel stamper on which a pattern was engraved, on a molding mold at molding. Further, the total reflection film is formed on the pattern of the molded substrate by a spattering method and the like (S1). A recording film is further formed on it in case of a rewritable disk.

[0025] The first intermediate layer 13 is formed on the Layer 1, which was formed by the above-mentioned manner (S2). The first intermediate layer 13 is a layer for enhancing adhesive force with the second intermediate layer 16 whose material is the 2P resin (Photo-polymer) which is formed later. An ultra violet rays curing type adhesive, a gluing agent, a pressure sensitive adhesive, a dry photo polymer sheet and the like are used as the material of the first intermediate layer 13. The second intermediate layer 16 (2P resin) is coated on the first intermediate layer 13, and a pattern is transcribed by being pushed with a stamper on which the information pattern of the layer 0 was engraved. Since the 2P resin has week adhesive force with a metal, the adhesive force can be enhanced by inserting the intermediate layer which is an adhesive layer, between the 2P resin layer and Layer 1.

[0026] Hereat, a conventional technology utilizes a nickel stamper as a stamper. However, the next generation optical disk takes the mode of two layers at one side, therefore since the incident face of laser light becomes a reverse side (cover layer side) against a molded substrate, the total reflection film is provided on the first molded substrate as Layer 1. Accordingly, even if Layer 0 is formed by the nickel stamper and the 2P resin, ultra violet rays cannot be irradiated because the 2P resin is sandwiched by the total reflection film and the nickel stamper, and the 2P resin cannot be cured. The aspect is shown by FIG. 2A, and it can be grasped that ultra violet rays cannot be irradiated from the nickel stamper side and the total reflection film side.

[0027] Accordingly, in the present invention, the molded substrate 14 is prepared as shown in FIG. 1, the semi-transparent film of a metal is formed on it by a spattering method and the like, and it is used as the semi-transparent stamper (S3). It is illustrated in FIG. 2B to cure the 2P resin by ultra violet rays. The information pattern of the layer 0 is engraved on the molded substrate 14, and a polycarbonate, PMMA, an amorphous polyolefin and the like are used as a material, and it is made by injection molding by the nickel stamper in like manner as the first molded substrate. Metals which has no adhesive force with the 2P resin such as, for example, aluminum, silver, gold and the like are used as the semi-transparent film.

[0028] Then, the transparent stamper 14 is pushed to the second adhesive layer (2P resin) 16, it is cured by irradiating ultra violet rays through the transparent substrate, the pattern of the transparent stamper is transcribed on the 2P resin (S4). Then, it is pealed at the interface of the semi-transparent metal film 15 and the 2P resin 16 (S5). Further, the semi-transparent film 17 (the semi-transparent recording film in case of a rewritable disk) is formed on the pealed 2P resin by a spattering method and the like to make Layer 0 (S6). Finally, the cover layer 18 is formed on it, and the optical disk with two layers on one side is completed (S7).

[0029] According to the above-mentioned production process, the problem that the 2P resin is not cured because the nickel stamper does not transmit ultra violet rays in the production of the next generation optical disk with two layers at one side, can be dissolved, and further, the semi-transparent stamper which is used here is composed of the molded substrate which can be formed by the usual production process of an optical disk and the semi-transparent metal film, therefore a special additional facility for preparing a stamper is also unnecessary, and the semi-transparent stamper can be easily produced in large quantities on the existing production line. Accordingly, it becomes possible to easily produce a sure optical disk with two layers at one side.

[0030] According to the above-mentioned various modes of operation, the skilled in the art can easily realize the present invention, but further, the skilled in the art can easily conceive the idea of various modified examples of these modes of operation, and it is possible to be adopted to the various modes of operation without having an inventive ability. The present invention reaches to a broad range which is not inconsistent with the disclosed principle and new characteristics, and is not limited to the above-mentioned modes of operation.

[0031] According to the method of the optical disk using the semi-transparent stamper of the present invention, it is capable of using 2P resin by an irradiation of ultra violet rays over the stamper, so that 2P resin can be used to manufacture the next generation optical disk with two layer at one side.

[0032] Further, the stamper is one obtained by the material and processes equivalent to a usual optical disk, can be easily produced in large quantities by the existing DVD production process without the necessity of an additional facility, and can be used as a cheap and disposable stamper. 

What is claimed is:
 1. A production process of an optical disk, wherein when a layer of an ultra violet rays curing resin which constitutes a portion of an optical disk is formed, a semi-transparent film of a metal is formed on a molded substrate on which a pattern was transcribed and this molded substrate is used as a semi-transparent stamper.
 2. A production process of an optical disk, comprising: a step of forming a first thin film on a first substrate; a step of forming a layer of an ultra violet rays curing resin on the first thin film; a step of forming a semi-transparent stamper in which a semi-transparent film of a metal was formed on a transparent molded substrate on which a pattern is transcribed, by injection molding in like manner as an optical disk; and a step of curing the ultra violet rays curing resin layer by irradiating ultra violet rays through the semi-transparent stamper.
 3. A production process of an optical disk according to claim 2, further comprising: a step of forming a second thin film on the ultra violet rays curing resin layer which was cured; and a step of forming a cover layer on the second thin film.
 4. A production process of an optical disk according to claim 2, wherein the semi-transparent stamper is formed by a polycarbonate as a raw material.
 5. A production process of an optical disk according to claim 2, wherein the semi-transparent stamper is formed by PMMA as a raw material.
 6. A production process of an optical disk according to claim 2, wherein the semi-transparent stamper is formed by an amorphous polyolefin as a raw material.
 7. A production process of an optical disk according to claim 2, wherein the semi-transparent film of a metal which is used for the semi-transparent stamper is formed by aluminum as a raw material.
 8. A production process of an optical disk according to claim 2, wherein the semi-transparent film of a metal which is used for the semi-transparent stamper is formed by silver as a raw material.
 9. A production process of an optical disk according to claim 2, wherein the semi-transparent film of a metal which is used for the semi-transparent stamper is formed by gold as a raw material.
 10. A production process of an optical disk according to claim 2, further comprising a step of forming an intermediate layer for adhering the first thin film with the ultra violet rays curing resin, on the first thin film after forming the first thin film on the first substrate.
 11. A production process of an optical disk according to claim 10, wherein the intermediate layer is formed by an ultra violet rays curing type adhesive.
 12. A production process of an optical disk according to claim 10, wherein the intermediate layer is formed by a gluing agent.
 13. A production process of an optical disk according to claim 10, wherein the intermediate layer is formed by a pressure sensitive adhesive.
 14. A production process of an optical disk according to claim 10, wherein the intermediate layer is formed by a dry photo polymer sheet.
 15. An optical disk comprising; a first substrate: a first thin film layer which was formed on the first substrate; and the layer of an ultra violet rays curing resin which was cured by irradiation of ultra violet rays using a semi-transparent stamper in which a semi-transparent metal film was formed on a transparent molded substrate which was formed on the first thin film layer and on which a pattern was transcribed.
 16. An optical disk according to claim 15, further comprising: a second thin film on the ultra violet rays curing resin layer which was cured; and a cover layer which is provided on the second thin film.
 17. An optical disk according to claim 15, wherein the semi-transparent stamper is formed by one of a polycarbonate and PMMA and an amorphous polyolefin.
 18. An optical disk according to claim 15, wherein the semi-transparent metal film which is used for the semi-transparent stamper is formed by one of aluminum, silver, and gold as a raw material.
 19. An optical disk according to claim 15, further comprising the intermediate layer for adhering the first thin film and the ultra violet rays curing resin between both on the first substrate.
 20. An optical disk according to claim 19, wherein the intermediate layer is formed by one or an ultra violet rays curing type adhesive, a gluing agent, a pressure sensitive adhesive, and a dry photo polymer sheet. 